1. Field of the Invention
The present invention relates to a logging system for wireless communication and a wireless device that is used in the logging system and performs communication wirelessly. The logging system of the present invention collects a log showing a communication status of the wireless device.
Priority is claimed on Japanese Patent Application No. 2009-036733, filed Feb. 19, 2009, the content of which is incorporated herein by reference.
2. Description of the Related Art
All patents, patent applications, patent publications, scientific articles, and the like, which will hereinafter be cited or identified in the present application, will hereby be incorporated by reference in their entirety in order to describe more fully the state of the art to which the present invention pertains.
In developing or setting a wireless device, collection of a log that shows an actual communication status of the wireless device and confirmation of contents of the log are performed. These are performed to confirm that the wireless device functions properly, and are very important. It is necessary to collect the log without affecting the communication performed by the wireless device. This is achieved, for example, by a method that uses a plurality of wireless devices. The log of a target wireless device is a target that is collected. A receiving wireless device that is different from the target wireless device receives or captures the log of the target wireless device.
When the log that shows the communication status of the target wireless device is collected by using the above method, a logging system that connects the receiving wireless device and a logging device with a communication cable is used. The logging device is achieved by a personal computer or the like. In this case, a channel on which the receiving wireless device performs capturing is set, and an operational mode of the logging system is set as a promiscuous mode. The promiscuous mode is a mode in which all data that are communicated on the set channel are received regardless of the destination of the data.
After the above settings are finished, the receiving wireless device starts capturing by an instruction of starting. The instruction of starting is output from the logging device and received by the receiving wireless device. After the capturing is started, the log captured by the receiving wireless device is collected in the logging device through the communication cable sequentially. A time stamp showing a time when the log is collected to the logging device is attached to the log. The log with the time stamp is recorded in the logging device. The log collected in the logging device is arranged by the time stamp, and the communication status of the target wireless device is confirmed in time sequence. Details of the conventional logging system for wireless communication are described in the following nonpatent literatures.
[Nonpatent Literature 1]
    SmartRF™ Protocol Packet Sniffer User Manual Rev. 1.10, Texas Instruments, URL: http://focus.ti.com/lit/ug/swru187b/swru187b.pdf[Nonpatent Literature 2]    WiSens™ Classic PACKET SNIFFER-IEEE 802.15.4/ZigBee™, BzWorks, URL: http://www.bzworks.com/library/downloads/WiSens_Datasheet.pdf[Nonpatent Literature 3]    An advanced wireless packet sniffer can help you get the full picture of your 802.11 WLAN traffic, TamoSoft, URL: http://www.tamos.com/products/commwifi/wifi-sniffer.htm
In the conventional logging system described above, only the log that shows the communication status of the channel that is set beforehand can be collected. The log that shows the communication status of the channel other than the channel that is set up beforehand cannot be collected. Therefore, in the communication method that uses a plurality of channels and switches the current channel or in the communication method that uses the plurality of channels in parallel, the log that is necessary to confirm the communication status when developing or setting the wireless device cannot be collected.
The communication method that uses the plurality of channels and switches the current channel is, for example, a Frequency Hopping Spread Spectrum method, hereinafter referred to as a FHSS method. In the FHSS method, the communication is performed with switching the current channel that is used in the data communication in a short time interval. The switching of the channel is to reduce a bad effect on the communication by noise from the outside. Typical examples of communication standards that use the above described method is Bluetooth™, IEEE 802.11, and the like.
When the switching pattern of the channel in the target wireless device is known, the log can be collected by switching the channel in the receiving wireless device in the same switching pattern as in the target wireless device. The channel switching in the target wireless device and the channel switching in the receiving wireless device need to be performed synchronously. The channel switching in the receiving wireless device needs to be performed in a short time. It is difficult to realize the above described method.
The above described communication method uses a plurality of channels at the same time. As a result, speed of data transmission can be increased. For example, in a mesh-type network, a specific channel is applied to the communication between specific wireless nodes, and information for controlling the communication is transmitted by using the specific channel. As a result, a plurality of wireless nodes that are in the area that radio waves can reach can perform communication at the same time. In the above described wireless system, a communication content of the specific channel may be influenced by a communication result of another channel. Therefore, the logs of all channels need to be collected, but the logs of all channels cannot be collected by the conventional logging system for wireless communication.